


Familiar Faces: Appendix

by Sinsational (Suukarin)



Series: Brotherswap [2]
Category: Undertale (Video Game)
Genre: Appendix work to an existing fic, Underswap Sans
Language: English
Status: In-Progress
Published: 2016-09-28
Updated: 2016-09-28
Packaged: 2018-08-18 08:00:08
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,101
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8154964
Author URL: https://archiveofourown.org/users/Suukarin/pseuds/Sinsational
Summary: Déjà vu is a strange thing to live through. 
(Collection of side stories to "Familiar Faces." These won't make much sense outside the context of the parent work.)





	

**Author's Note:**

> (This takes place between chapters 10 and 11.)

If she'd thought about it, she would have worn her jacket, but Undyne’s never really touted herself as one who uses her head in the intended use of the phrase. Instead, she just knocks harder on the front door of Papyrus’ house, ignoring the chill that tries to freeze her in place. 

In all honesty, she'd rather not be here at all -- she'd almost written the perfect letter to Alphys, and had been so close to just sealing the envelope and sliding it under the lizard’s lab door. Few things are more important to her than Alphys…

But Papyrus hasn't showed up for training in over a week, and today, he's not answering her calls. 

“ _ Papyrus! _ ” she hollers, wrapping her arms around herself. “Answer the freakin’ door already, it's  _ cold _ out here! I  _ know _ you're in there!”

She  _ hopes _ he's in there, at least, and briefly contemplates even kicking down the door and replacing it later--

There's a jiggle of someone turning the lock, and the front door creaks open. 

Undyne blinks.

“ _ Sans? _ ”

“Sans” blinks his impossibly blue, impossibly  _ unSanslike _ eyes at Undyne, and darts back into the house, leaving the door open behind him. 

“ _ Papy! _ ” he shouts, his voice full of an enthusiasm Undyne’s never heard from him before. “Undyne is here, you should come down and say hi!”

Undyne awkwardly walks inside, and kicks the door shut behind her. 

Everything else looks the same, but she can't take her one good eye off of “Sans” -- if this even really  _ is _ Sans. He's about the right height, and still has that perpetual annoying grin that drives her nuts, but everything else -- from his wide, starry-eyed expression to the gray and blue garb he wears -- just doesn't seem to  _ fit _ . 

Before she can fix him with a scowl, however, Undyne hears the rattle of a doorknob from upstairs, followed by a door creaking open. 

“OH, HELLO, UNDYNE! I DIDN'T HEAR YOU AT THE DOOR…”

She takes one look at Papyrus -- and balks at the sight of him in a dark grey turtleneck and flannel pants with bones printed on the fabric. 

Undyne can't remember the last time she saw him out of his battle body. 

“Papyrus, are you alright?!” she demands, bounding up the stairs to meet Papyrus halfway. “You didn't answer your phone! I was _ worried _ about you! And you're not even in your battle armor?!”

“O-OH, SORRY,” Papyrus apologizes, and Undyne misses the meekness in his gesture.  “I'VE, UM, I'VE BEEN BUSY LOOKING FOR SANS, SO I MIGHT HAVE NOT HEARD YOUR CALL… S-SORRY ABOUT THAT…”

Undyne frowns, glancing back down the stairs at “Sans” standing nervously in the living room. 

“Is that not him right there, Papyrus?” she growls, tensing as if preparing to strike. 

“IT -- IT'S A LONG STORY, UNDYNE, AND--”

“ _ Find a way to make it short, _ ” she seethes, gripping the handrail and splintering the wood in her grasp. 

“UNDYNE--”

“I-I'm Sans from a different timeline!” “Sans” squeaks, eyes wide with fright. “I-I just woke up in this world one day and Papy took me in and I've been living here until we find a way to get me back home!”

An awkward silence fills the house, until Undyne finally lets go of the handrail. 

“Maybe make it a little longer than that,” she clarifies, rubbing her temples. “ _ Who _ are you, exactly?”

“U-um, well…”

* * *

Undyne sets her tea on the end table, slumping back into the couch.

“So,  _ he's _ Sans… but from a timeline where everyone else is flipped?” she asks, as though not entirely certain of what she's just heard. 

“Yep!” Sans nods, his voice still filled with an enthusiasm that's foreign to her ears. “Papy’s been letting me stay here while Al -- uh,  _ Dr.  _ Alphys tries to find a way back. We're hoping it won't be long, though, ‘cause I -- I miss my brother, and Papy, he…”

As Sans trails off, fixing Papyrus with an uneasy look, Undyne realizes that Papyrus has been oddly silent this whole time. 

“What's it been like for you, Papyrus?” she asks, lightly thwacking the taller skeleton on the back. “Living with two versions of your brother must be, uh, pretty nuts!”

“...Y-YEAH, IT'S BEEN…”

Undyne notices the way Papyrus curls his hands in the fabric of his pants, and pauses before she takes a look around. 

“...Papyrus, where…  _ is  _ your brother?” she finally says, her words laced with a caution she's not used to using. “I didn't see him on my way over from Waterfall…”

“SANS IS… HE'S…”

The more he fumbles for his words, the more Undyne’s heart sinks, until Sans suddenly clears his throat. 

“He's taking care of important business with my brother!” he declares with great certainty as he puts a hand on Papyrus’ shoulder. “He just had to leave so quickly, he forgot to bring his phone or leave a note… but he'll be back! And then my brother will take me back home, and everything will be A-okay!”

“YEAH!” Papyrus nods, but Undyne can hear the forced cheeriness in his voice. “AFTER ALL, MY BROTHER WOULD NEVER GO ANYWHERE WITHOUT TELLING ME UNLESS IT WAS EXTREMELY IMPORTANT! SO… SO WHATEVER IT IS HE'S DOING, HE JUST COULDN'T TELL ME BEFORE HE LEFT! I JUST HAVE TO REMEMBER THAT!”

He turns to look Undyne in the eye, beaming. 

“RIGHT, UNDYNE?”

She sees the strain on his smile, and traces of fear in the corners of his normally worry-free eyes, and Undyne forces an awkward smile of her own before she pulls Papyrus into a bone-crushing hug. 

“Of course, Papyrus,” she agrees, swallowing her own lie. “But until he gets back, I think I'm gonna crash here to look after you. Think of it like an extended slumber party, you punks.”

“CAN WE COOK SPAGHETTI?”

“And tacos?!” Sans chimes in, eyes lighting up. 

“We'll make  _ spaghetti tacos! _ ” Undyne declares, not yet prying herself away from Papyrus. “And every day, we'll have warrior's training until we puke! So that when your brothers come back, we can clobber ‘em for making us all worry!”

“ _ Yeah! _ ”

“I CAN'T WAIT TO HAVE A SLEEPOVER WITH MY FRIENDS!” Papyrus declares cheerily, and Undyne can feel the familiar unbridled joy rolling off of his bones once more. “THIS IS GOING TO BE A LOT OF FUN!!”

“It sure is, punk!” Undyne grins toothily as she finally separates from Papyrus. “I hope you're ready for japes until your heads explode!”

The skeletons’ excited cheers are not enough to distract Undyne from the quiet fury in her heart as she plots all the ways to make Sans pay for letting his brother suffer. 


End file.
